A popular class of motor vehicles, commonly known as multi-purpose vehicles, has three or more rows of seating with at least one row of seats readily removable from the vehicle. One of the anchoring points of a seat belt for such a removable seat is a buckle that is attached to the seat base, and is referred to in the art as a sill end fixing buckle. A buckle tongue that is attached to the seat belt webbing is normally retained in the sill end buckle until the vehicle seat is required to be removed from the vehicle. Customer Surveys have found that owners of this type of vehicle have tried to remove the seat with the sill end tongue still engaged causing aggravation and unnecessary stresses on the seat belt structure. The present invention solves this problem by ensuring that the sill end buckle tongue will be automatically released from the buckle when the seat is being removed or repositioned in the vehicle. While the invention has particular applicability to the center seat in a row of seats, it can be employed with seats in any location in the vehicle.